This has been mentioned before, but for those not in the know, if you are over 60 [majority of the forum!] you are eligible for a 20% discount on crossings.
You cannot access this online but have have to phone your order in. The number differs depending upon the route so you will need to check the website. It states 13p per minute, but I'm now led to believe this is included in most users' phone contracts as it is an 0330 number. This code is for a non area-specific replacement to an 0800 number.
Only problem with Dieppe-Newhaven (correct, I have booked it from France) is there would appear to be only one day in Sept or Oct with a civilised crossing time of 11:00am. Dover to Calais/Dunkirk prices are yet to go live for next summer but they may include a free meal.

Colin

We've had this crossing booked for over a year now and hope to use it next Spring (at last). Since we booked, the price has come down a lot and they have also put us on a day crossing instead of overnight.
We are paying £327 return for two people, a cat , a car and an Eriba. Quite happy with that.
Randa

They advertise three crossings a day but with the exception of 11am on 30th Sept [lucky for me] they seem to have only two. These are about 1am and 6pm. My crossing should have been £168 before the discount, £134 after.

Colin

ps not sure if the 20% is valid on other routes. It would be wort a call.